The real-life Poseidon adventure

When the British submarine HMS Poseidon sank off China's
east coast 82 years ago after colliding with a cargo ship, the dramatic
underwater escape by five of its crew members made headlines around the
world.

But the episode was soon overshadowed by the communist
insurgency already raging on the mainland, the Japanese invasion of
Manchuria, and eventually the outbreak of the second world war. The
world moved on, the wreck of the Poseidon lay 30 metres beneath the sea,
lost to history.

Until now. A new book reveals that China
secretly salvaged the submarine in 1972, perhaps to abet its
then-incipient nuclear submarine programme.